1. Field of the Art
This invention relates to compositions for imparting fire-retardant properties to polyester fibers.
Imparting fire-retardant properties to fiber products has been already regulated for certain applications of the fiber products. Fiber products which are required to be rendered fire-retardant include a wide variety of fiber products such as curtains, tents, awnings, sheets, interior ornaments, decorations, automobile interior articles and garments, or example. Impartation of fire-retardant properties to such fiber products is to minimize casualties due to fires by reducing the number of sources of fire occurrence or preventing fires from spreading.
2. Prior Art
Impartation of fire-retardant properties to fiber products can be performed by the so-called temporary deposition method in which a fire-retardant agent is caused to temporarily adhere to fibers or the permanent deposition methods (1) the fire-retardant agent is caused to chemically react with the fibers, (2) the agent is applied to fibers by means of resin, (3) the agent is caused to permeate into fibers by means of the so-called high temperature and pressure or carrier dyeing and (4) the agent is forced into fibers.
As to agents for imparting fire-retardant properties to polyester fibers as a post-treatment for the fibers, a variety of alkylphosphoric esters containing chlorine or bromine have been employed and such agents include, for example, (1) tris(2,3-dibromopropyl)phosphate, tris(2,3-dichloropropyl)phosphate and trischloroethyl phosphate, (2) condensed phosphoric esters containing bromine or chlorine, (3) aromatic systems such as hexabromobenzene, tetrabromotoluene and decabromodiphenyl ether and (4) as aliphatic system, cycloalkane such as hexabromocyclododecane. Any one member selected from the above-listed fire-retardant agents is dispersed in water or an emulsifying agent. The agent dispersed in the liquid is added to a high temperature and pressure dyeing bath or ambient pressure carrier dyeing bath for dyeing polyester fibers and the resulting dyeing bath is applied to polyester fibers to dye and at the same time to impart fire-retardant properties to the polyester fibers. According to another prior art method for imparting fire-retardant properties to polyester fibers, the polyester fibers are immersed in a liquid in which a fire-retardant agent is dispersed or emulsified and then cured at a temperature in the range of 170.degree.-195.degree. C. for 30-90 seconds to thereby permeate or distribute the agent into the fibers.
However, the above-mentioned prior art methods and agents for imparting fire-retardant properties to polyester fibers have their inherent many drawbacks in treating polyester fibers. That is, most of alkylsulfuric esters exhibit high virulence for human bodies and some of the esters are mutagenic and carcinogenic. And when alkylsulfuric ester is used for imparting fire-retardant properties to polyester fibers, since an emulsion of the ester is added to a dyeing bath, the emulsified ester obstructs the absorption of the dyestuff in the dyeing bath into polyester fibers and thus, the dyestuff may not be applied to the polyester fibers in an intended amount. Also when alkylsulfuric ester is employed for imparting fire-retardant properties to polyester fibers by the thermosol process, the treated polyester fibers exhibit a peculiar oily touch resulting in substantial reduction of the quality of the fibers. The most important drawback inherent in the prior art fire-retardant agents is that they substantially reduce the color fastness and especially, the sun fading resistance of the treated polyester fibers.
Aromatic bromine compounds as fire-retardant agents are very low in the absorption rate into polyester fibers and difficult to be deposited on the fibers in an amount sufficient to impart fire-retardant properties to the fibers. Thus, the aromatic bromine compounds are not suitable as the fire-retardant agents for polyester fibers. Aliphatic halogen compounds are dispersed in water and added to a dyeing bath or the compounds are employed by the thermosol method. Although the compounds are dispersed in water to be added to a dyeing bath or employed by the thermosol method and have less adverse effect on the treated polyester fibers, the absorption rate of the compounds into the fibers as determined by the dyeing bath absorption determination method is quite low such as about 25% with the employment of the agents by 5.0% o.w.f. (of the weight of polyester fibers to be treated) and the use of the aliphatic halogen compounds as fire-retardant agents for polyester fibers is uneconomical. And since the absorption rate of aliphatic halogen compound into polyester fibers is low as mentioned above, a portion of the hard-to-combustion property impartation agent tends to contaminate the dyeing machine and dyestuff liquid circulation pipe or pipes employed and ultimately, deposits itself on the wall or walls of the machine and/or pipe or pipes in the form of scale which interferes with the succeeding dyeing operations. Furthermore, since a substantial portion of the fire-retardant agent is not dissolved, but dispersed in the liquid, the agent can not be employed in atomizing type and cheese dyeing machines because the agent develops the so-called filtering phenomenon in such machines.